1. Field of the Invention
The present invention relates to a dishwasher and, more particularly, to a self-drainage preventing structure that can prevent, when a filter mounted in a sump is blocked by foreign objects, washing water from being self-drained to an external side through a drain pump.
2. Description of the Related Art
Generally, a dishwasher is a machine that washes and dries dishes loaded on upper and lower racks by spraying washing water pumped by the washing pump toward the upper and lower racks through spraying nozzles. The dishwasher includes a tub defining an outer appearance of the dishwasher, at least one rack disposed in the tub to load dishes, at least one spraying nozzle for spraying washing water to surfaces of the dishes, and a sump assembly mounted on a floor of the tub to reserve the washing water. Food waste adhered to the dishes are removed from the dishes by pressure applied by washing water sprayed from a spraying nozzle.
A filter is mounted in or on the top surface of the sump assembly to filter foreign objects such as food residue. The filtered foreign objects are collected in a foreign object collecting chamber formed in the sump assembly.
When the foreign objects are excessively accumulated in the foreign object collecting chamber or the washing water excessively contains foreign objects, the washing water cannot pass through the filter but stays in the drain pump connected to the foreign object collecting chamber. When the washing water is continuously accumulated in the drain pump, the drain pump cannot be operated by the pressure of the washing water. Even in this case, a part of the washing water is drained through a drain hose connected to the drain pump.
At this point, a pressure sensor or a pressure switch that is installed on a lower end of the drain hose detects this to forcedly drain the washing water.
However, when the pressure sensor or the pressure switch is installed, the manufacturing cost increases and the assembling process is complicated. Furthermore, when the pressure sensor or the pressure switch malfunctions, the self-drainage may be detected.